The present disclosure relates to approaches for reformulating a variety of yellow pyrotechnic compositions so as to limit environmentally objectionable perchlorate ingredients while still providing acceptable performance when compared to in-service signal flare devices.
Pyrotechnics are used in a variety of applications. One such application is colored signal flares. Many such pyrotechnic flare compositions include chlorate or perchlorate oxidizers. Residual perchlorates from these devices may be absorbed into groundwater and require remediation.
In the past, the vast majority of red, green, and yellow signal flares have used perchlorate ingredients to produce their desired colors. This has contributed to an increase in the total concentration of perchlorate residues at various sites, such as military and industrial sites, and to generally higher than desired concentration in drinking water supplies. Clearly, any methods that can be used to limit the perchlorates and minimize any other chlorine-containing ingredients would be an environmentally noteworthy advance in the state of the art.
The U.S. Navy has had an in-service yellow flare perchlorate-containing composition (IS Y 1). IS Y 1 has had a product improvement replacement, the Yellow signal flare (IS Y 2). IS Y 2 uses the same composition as IS Y 1. As shown in Table 5, IS Y 2 contains approximately thirty point three weight percent (30.3%) Granulation 18 magnesium fuel, approximately nineteen point eight weight percent (19.8%) sodium oxalate, approximately twenty weight percent (20%) barium nitrate, approximately twenty-one weight percent (21%) potassium perchlorate, approximately four weight percent (4%) asphaltum, and approximately five weight percent (5%) binder. The binder includes within the range of approximately seventy percent (70%) to approximately eighty percent (80%) Epon™ Resin 813 epoxy and within the range of approximately twenty percent (20%) to approximately thirty percent (30%) Versamid® 140 curing agent. Accordingly, it was this composition that formed the starting point in the new perchlorate-free yellow signal flare formulations disclosed in the present patent.